The accurate prediction of aerodynamic drag on satellites orbiting in the upper atmosphere is critical to the operational success of modern space technologies, such as satellite-based communication or navigation systems, which have become increasingly popular in the last few years due to the deployment of constellations of satellites in low-Earth orbit. As a result, physics-based models of the ionosphere and thermosphere have emerged as a necessary tool for the prediction of atmospheric outputs under highly variable space weather conditions. This paper proposes a high-fidelity approach for physics-based space weather modeling based on the solution of the Navier-Stokes equations using a high-order discontinuous Galerkin method, combined with a matrix-free strategy suitable for high-performance computing on GPU architectures. The approach consists of a thermospheric model that describes a chemically frozen neutral atmosphere in non-hydrostatic equilibrium driven by the external excitation of the Sun. A novel set of variables is considered to treat the low densities present in the upper atmosphere and to accommodate the wide range of scales present in the problem. At the same time, and unlike most existing approaches, radial and angular directions are treated in a non-segregated approach. The study presents a set of numerical examples that demonstrate the accuracy of the approximation and validate the current approach against observational data along a satellite orbit, including estimates of established empirical and physics-based models of the ionosphere-thermosphere system. Finally, a 1D radial derivation of the physics-based model is presented and utilized for conducting a parametric study of the main thermal quantities under various solar conditions.

翻译：精确预测高层大气中运行卫星所受气动阻力，对现代空间技术（如基于卫星的通信或导航系统）的运营成功至关重要。近年来，随着低地球轨道卫星星座的部署，这类技术日益普及。因此，基于物理的电离层与热层模型已成为在高度变化的空间天气条件下预测大气输出的必要工具。本文提出一种基于物理的空间天气高保真建模方法，该方法采用高阶间断伽辽金法求解纳维-斯托克斯方程，并结合适用于GPU架构高性能计算的无矩阵策略。该模型描述了一个由太阳外部激发驱动的、处于非静力平衡状态的化学冻结中性大气热层。为处理高层大气中的低密度以及问题中存在的多尺度特征，本文引入了一组新型变量。同时，与大多数现有方法不同，径向与角度方向采用非分离方式处理。本研究通过一系列数值示例展示了该近似的准确性，并基于卫星轨道观测数据验证了当前方法，同时对比了已有经验模型与电离层-热层系统物理模型的估算结果。最后，推导了该物理模型的径向一维简化形式，并用于不同太阳条件下主要热学参数的参数化研究。